Switching mechanism



Sept. 30, 1941. J. M. WILSON SWITCHING MECHANISM Filed March 6, 1959 Fig. 1

inventor John M. Wilson 1.

actuating element.

Patented Sept. 30, 1941 2,257,439 7 SWITCHING MECHANISM I John M. Wilson, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a porporation of Delaware Application March a, 1939, Serial No. 260,071

20 Claims.

This invention relates broadly to a switch perating mechanism and more particularly to that type of mechanism in which a condition responsive device drives the switch actuating element through a slip friction connection so that the switch is actuated on a reversal in the trend of the condition value rather'than at any definite value.

In prior art devices of thisnature a condition responsive device operates a movable member and the switch operating element is carried by and connected to said member by means of a slip friction connection. The force available for actuating the switch in such a device is necessarily limited by the amount of friction between the movable member and the switch actuating element. If the frictional force is slight, only a slight force will be available to actuate the switch, and if this force is not suflicient the actuating element will merely slip on the operating member and the switch will not be actuated. If the frictional force is large a larger force will be available for+actuating the switch but the reversal loss in the condition responsive device will also be larger. By reversal loss is meant the difference in the condition value necessary to cause the condition responsive device to reverse the movement of the movable member. A large reversal loss is undesirable in that it reduces the sensitivity of the mechanism in responding to F a reversal in the trend of the condition value.

It is an object of this invention to provide a switching mechanism of the slip friction type wherein a large force is available for actuating the switch and yet only a small force opposes the slip between the movable member and the switch A further object is to provide a movable member which carries a clutch element normally clutched to it, and stops for simultaneously limby them, the arrangement being such that the first switch is closed before the second switch is opened on movement of the movable member in one direction, and the first switch is opened before the second switch is closed on movement of the movable member in the opposite direction.

A further object is to provide the movable member with a pair of legs and mount one of the clutch elements on each leg.

These and other objects will readily become apparent as the specification is read in the light of the accompanying drawing in which Figure 1 is a side elevation of one embodiment of my invention showing parts in section,

Figure 2 is a plan view of part of the mechanism, and

Figure 3 is a perspective view of the mechanism shown in Figure 2, the view being slightly expanded for the sake of clarity.

My invention has been illustrated in connection with a relay and combustion responsive thermostat for operating a series of switches in a desired manner for controlling the starting circuits for an oil burner. It will be appreciated however that this is but one use to which my invention may be put and that it is adaptable to many other-control applications.

iting the movement of the clutch element and tion element.

Another object is to mount two clutch type slip friction elements on the movable member and to provide a pair of switches to be actuated An additional object is to op erate a second switch with the same slip fric- A supporting structure Ii has been indicated in Figure 1 of the drawing and a tube I2 is suitably secured at one end to the supporting structure, tube I! has an inwardly bent ear i3 at its opposite end for supporting one end of a thermal element It in a suitable manner such as the bolt l5 and nut IS. The specific thermostat illustrated forms the subject of application Serial No. 118,742 filed January 2, 1937, in the names of Willis H. Gille and George A. Bouvier, and is therefore not a part of the present invention.

The opposite end of the thermostatic element I4 is suitably connected by means of nut I! to a reduced end of connecting rod l8 which extends through a hole in ear 22 of tube i2 and is connected at its opposite end to an insulating memher l9 by means of the screw threads 20 and lock nut H. The insulating member I8 is connected to a second connecting rod 23 by means of screw threads 24 and lock nut 25. Connecting rod 23 is connected to the U-shaped operating member generally indicated at 21 by means of the lock nuts 28 which are threaded on the connecting rod 23 as shown in Figure 2. The operating member 21 will therefore be moved back and forth by the thermostatic element It in accordance with temperature changes'at that point.

An insulating panel 38, a portion of which is shown in Figure 2, is supported by the structure U. The operating member 21 extends through a hole 3| in the panel 38 and if desired a plate such as indicated at 32 may be connected by means of screws 33 to the inner face of the panel in order to form a bearing and guide for the operating member 21.

Referring now more particularly to Figure 3 the leg 35 of the operating member 21 carries a clutch element 36 by means of a hole 31 which is slightly over size with respect to the leg 35. A leaf spring 38 is suitably connected to the clutch element 36 as by the rivets 39 and bears against the underside of the leg 35 for the purpose of biasing the clutch element 36 in a clockwise direction. The result of this bias is to turn the clutch element 36 so that the edges of the hole 31 are forcibly held against the leg 35 to produce a more or less positive driving connection between the two elements. As the leg 35 is moved back and forth the clutch element 36 will be operative to actuate any mechanism with which it may be associated. Stops 48 and 4| are placed in the path of movement. of the clutch element 36 in order to limit its movement by the leg 35. As the leg 35 movesto the left it will carry the clutch element 36 with it until the element engages the stop 48. The pressure of the clutch element 36 against the stop 48 caused by further movement of the leg 35 to the left will tend to rotate the clutch element 36 slightly in a counter-clockwise direction and this rotation will release the forcible-engagement of the edges of the hole 31 and the leg 35 so that the leg 35 w ll be free to move through hole 31 in the clutch ement 36 with a minimum of resistance. As th leg 35 reverses and moves toward the right the pressure of the clutch element 36 against stop 48 will be relieved and the leaf spring 38 "il again be operative to rotate the clutch elen 36 slightly in a clockwise direction until rises of the hole 31 forcibly engage the leg nd the clutch element will therefore be moved the right with the leg 35 and will again be *perative to actuate any mechanism with which ay be associated. On continued movement the clutch element will engage the stop 4| which w ll limit its movement and rotate it slightly in a counter-clockwise direction to disengage the edges of the hole 31 with the leg 35. This releases the clutching action between the two elements and the leg 35 will therefore be comparatively free to continue its movement to the right. Again as the leg 35 reverses its movement the leaf spring 38 will reengage the edgesof the hole 31 with theleg 35 and the clutch-element 36 will therefore be driven to the left by the leg 35.

It will be seen that the clutch element 36 isalwaysactuated upon a reversal in movement of member 21 caused by a reversal in temperature change and hence its actuation is independent of any definite degree of temperature.

Leg 43 of the.operating member 21 carries a clutch element 44 heaving an oversized hole 45 therein through which the leg 43 is inserted. Leaf spring 46 connected to the clutch element by means of the rivets 41 operates to bias the clutch element 44 for rotation in a counter-clockwise direction causing the edges of the hole 45 to engage the leg 43 so that the clutch element 44 will be driven by the leg 43 in the same manner as clutch element 36 is driven by the leg 35. The clutch element 44 is provided with a pair of stops 48 and 49 which serve tolimit the movement imposed upon the clutch 44 and simultaneously release the clutching action between the element 44 and leg 43 in the same manner as in connection with the element 36 and leg 35. Clutch 44 is therefore also actuated in response to a reversal of temperature change and not upon any definite temperature. I

Referring now to Figures 1 and 2 it will be seen that a U-shaped bracket generally indicated at 53 is supported on the panel 38 by engagement of screws 54 with the feet 55 of the bracket 53. Two portions of the bracket extend outwardly and are inserted through holes in a plate 56 and form the means by which this plate is staked to the bracket 53 as indicated at 51 and 58. Leg 58 of the bracket 53 is provided with a slot as indicated at 68 in Figure 1. The stop 48 rides in the slot 68 and is provided with a pair of ears 6| with which the screw 62 has screw threaded engagement as shown in Figure 2. The screw 62 is journalled in the plate 56 as shown at 63 in Figure 2 and rotation of this screw will adjust the stop 48 back and forth in the slot 68. Spring 64 provides a frictional engagement between the stop 48 and leg 59 to prevent accidental movement of the stop 48. A second slot 65 in the leg 58 slidably carries the stop 4| which may be secured in adjusted position by means of the washer head screw 66.

Leg 61 of the bracket 53 is also provided with a slot in which the stop 48 is slidably mounted. The ears 68 of stop 48 screw threadedly receive the screw 69 which is journalled in the blade 56 as indicated at 12. Rotation of screw 63 will therefore adjust the stop 48 back and forth with respect to the bracket 53. Spring .13 provides sufficient friction between stop 48 and leg 61 to prevent accidental displacement of stop 48. Stop 48 is shown in Figure 2 as being fixedly secured to leg 51 by means of the rivets 1| but it will be appreciated that this stop can be-made adjustable in the same manner as stop 4| if desired.

Leg 35 of the operating member 21 extends through holes 16 in bracket 53 and 11 in plate 56 and the leg" extends through holes 15 in bracket 53 and 11 in plate 56. bracket 53 and plate 56 serve to guide and sup port the legs 35 and 43 of the operating member 21.

As shown in Figure 1 the bracket 88 screw threadedly receives an adjustable contact shown at 8|. As seen more clearly in Figure 3 the clutch element 44 carries at its lower end a resilient contact blade 82 having a contact, 83 which engages adjustable contact II. The stop 48 for clutch element 44 is so positioned that it will enage the element just after the contacts 8| and 83 have movedinto engagement so as to insure a good contact between them.

Pivotally mounted on a bracket 85 suitably secured to the panel 38 is a channel member 88 having a cam surface 81. The clutch element 36 has a rounded portion 88 at its lower end which cooperates with the cam surface 81 of the member 86. The member 86 is biased into engagement with portion 88 by means of a biasing spring 89, When the clutch element 36 is in its left hand position, as shown in Figure 3, the member 86 is shown in its raised position and when the clutch element 36 is in its right hand position, as shown in Figure 1, the member 88 has been lowered due to the fact that the clutch element 36 is engaging the high portion of the cam surface 81.

Mounted on the panel 38 is a bracket 98 carry- In this manner the original position.

ing a contact A second bracket mounted just behind the bracket 00 carries a second contact 02. A pair of spring contact blades 93, 94 carry two movable contacts 95 and 06 which cooperate respectively with the stationary contacts SI and 92. When the clutch element 36 is in its left hand position these contacts will be separated as shown in Figure 3 and when the clutch element is in its right hand position the contacts will be closed as shown in Figure 1. The contacts are so arranged that!" and 95 will engage before 92 and 96 as clutch element 36 moves to the right.

The bracket I00 which is suitably mounted on the panel 30 carries a relay winding IM and pivotally supports an armature I02 as shown at 09. Armature I02 carries a pair of spring contact blades I03 and I04. These contact blades are normally biased apart as shown in Figures 1 and 3 and the blade I04 carries an insulating member I05 having a downwardly extending abutment I06. When the relay winding is deenergized the armature drops out to the position shown in Figure 1, at which time the contact blades I03'and I04 are separated. If the relay winding MI is energized when the clutch element 36 is in its right hand position, as shown in Figure 1, the

flat portion I01 of the clutch element will engage tionary contacts H3 and H4 suitably mounted upon the panel 30.

The switching mechanism just described was designed for use in an oil burner control circuit act to materially reduce the friction through which the member 21 drives the elements on over run. This is a decided improvement over the usual type of slip friction element and provides for a comparatively large force by which the switches may be actuated and provides for a relatively small amount of friction opposing the continued movement of the movable member by the combustion responsive thermostat after the clutch elements have reached their limit position.

Certain modifications of this arrangement will undoubtedly occur to those who are skilled in the art and it is therefore understood that I intend to be limited only by the scope of the appended claims and not by th specific embodiment of my invention which is disclosed.

I claim as my invention:

1. A slip friction mechanism comprising a movable member, an element, a slip friction connection through which said member drives said element, and means materially reducing the friction afforded by said connection in response to movement of said element by said movable member.

2. A slip friction mechanism comprising a mov-. able member, an element moved by said member by means of a slip friction connection, and means limiting the movement of said element and simultaneously reducing the friction afforded by said connection.

3. A slip friction mechanism comprising a movable member, an element moved by said member by means of a slip friction connection,

7 and a stop engaged by said element, the pressure similar to the one disclosed in application Serial No.,77,758 filed May 4, 1936, in the name of Ernest M. Miller. 'In the normal operation of such a system when the parts are in cold position the relay winding IOI will be deenergized, the thermostat I4 will be contracted and the clutch elements 36 and 44 will be in their right hand positions at which time the contacts 9| and 95, and 92 and 96 will be in engagement and the contacts 8| and 83 will be separated. On a demand for heat the relay winding IOI will be energized closing all of the relay contacts including thecontact blades I03 and I04. This normally produces combustion causing expansion of the thermostat I4 which will move the operating member 21 to th left. Due to the fact that the stops 46 and 49 are very close together the clutch element 44 will move but a short distance before the contacts 8| and 83 will engage. Thereafter the clutch element 86 will move off of th high side of the cam surface 01 permitting the contacts 9| and 95, and 92 and 06 to separate and the portion I 01 will move off of abutment I00 permitting the contact blades I03 and I04 to separate. When the heat demand has been satisfied the relay IOI will be deenergized and the thermostat I4 will cool and return the parts to the It will be appreciated that the clutch elements used in this switching mechanism differ over the prior art devices in that the stops with which they cooperate act not only to limit the amount of movement of the clutch elements but they also of said element against said stop reducing the riction afforded by said connection.

4. A slip friction mechanism comprising a movable member, an element moved by said member by means of a slip friction connection, and a stop engaged by said element, the pressure of said element against said stop reducing the friction afforded by said connection thereby permitting further movement of said member in the same direction, reversal of movement of said movable member relieving said pressure whereby said element is substantially immediately moved by said member in the opposite direction.

5. A slip friction mechanism comprising a movable. member, a clutch element slldably mounted thereon and normally in clutched engagement therewith, and a stop for simultaneously stopping said element and declutching it with respect to said member thereby permitting free continued movement of said member in the same direction.

6. A slip friction mechanism comprising a movable member, a clutch element slidably mounted thereon, means tending to rotate said element with respect to said member whereby said element is clutched with respect to said member for movement'therewith, and a stop limiting the movement of said element by said mem ber and simultaneously rotating said element in a manner to declutch it with respect to said member. i

7. A slip friction mechanism comprising an element having a hole therethrough, a rod extending through said hole whereby said element is carried by said rod, said hole being slightly larger than said rod, meam tending to rotate said element with. respect to said rod whereby the edges of said element about said hole grip said rod, means to move said rod and hence said element, and means cooperating with said element to limit its movement by said rod and to simultaneously rotate said element slightly with respect to said rod in a manner to release its grip thereon.

8. A slip friction mechanism comprising an element having a hole therethrough, a rod extending through said hole whereby said element is carried by said rod, said hole being slightly larger than said rod, means tending to rotate said element with respect to said rod whereby the edges of said element about said hole grip said rod, said means comprising a leaf spring carried by said element and slidingly engaging said rod, means to move said rod and hence said element, and means cooperating with said element to limit its movement by said rod and to simultaneously rotate said element slightly with respect to said rod in a manner to release its grip thereon.

9. In a device of the character described, comprising in combination, a movable member, a clutch element slidably mounted thereon and normally in clutching engagement therewith, a contact moved by said element, a stationary contact, movement of said member causing engagement of said contacts, and a stop permitting substantially no movement of said element after said contacts have engaged and simultaneously declutching said element whereby said member may continue moving in the same direction.

10. In a device of the character described, comprising in combination, a movable member, a clutch element slidably mounted thereon and normally in clutching engagement therewith, a contact moved by said element, a stationary contact, movement of said member causing engagement of said contacts, a stop permitting substantially no movement of said element after said contacts have engaged, said stop simultaneously declutching said element whereby said member may continue moving in the same direction, reversal of movement of said member permitting said element to reclutch said member and move with it, and a second stop limiting movement of said element in said last mentioned direction and simultaneously declutching said element from said member, said first mentioned stop being adjustable.

11. In a device of the character described, comprising in combination, a movable member, condition responsive means for moving said member in a substantially longitudinal direction, a pair of clutch elements mounted on said member and normally clutched thereto for movement therewith, a switch and a pair of stops associated with each element, said stops when engaged by said elements operating to declutch them with respect to said member, the arrangement being such that on movement of said member in one direction one of said elements will first close its switch and engage one of its stops and the other element will first open its switch and then engage one of its stops, and on movement or said member in the other-direction said one element will first open its switch and then engage the other of its stops and the other element will first close its switch and then engage the other of its stops,

the stops of said one element being located closer together than the stops of said other element .whereby said one element always actuates its connection after said switch has been actuated whereby said member may continue to move treely in the same direction under the infiuence of said combustion responsive device, said connection being reestablished immediately upon reversal of said member.

13. In a device of the character described comprising in combination, a movably mounted armature, a pair 0! normally open contacts carried by said armature, an element cooperating with said contacts, a condition responsive device for moving said element between first and second positions, and means attracting said armature, said contacts being closed only by attraction oisaid armature when said element is in said first position, movement of said element to its second position permitting opening of said contacts.

14. In a device of the character described comprising in combination, a movably mounted armature, a pair of normally open contacts carried by said armature, an element cooperating with said contacts, a condition responsive device for moving said element by means of a slip friction connection, first and second stops for limiting the movement oi said element between first and second positions, a second switch closed by said element when it is in its first position and opened when said element is in its second position, said contacts being closed only by attraction of said armature when said element is in said first position, movement of said element to its second position permitting opening of said contacts.

15. In a device of the character described comprising in combination, a movably mounted armature, a pair of normally open contacts carried by said armature, a movabl member, a clutch element slidably mounted on said member but normally in clutched relation therewith, a pair of stops limiting the movement of said element between first and second positions and simultaneously declutching said element with respect to said member, means for attracting said armature, and a second switch closed by said clutch element as it moves to said first position and opened as it moves to said second position, said contacts being closed only by attraction of said armature when said element is in said first position, movement of said element to its second position permitting opening of said contacts.

16. In a device of the character described comprising in combination, a movable member, a condition responsive device for moving said member longitudinally, an element having a slip friction engagement with said member and movable longitudinally therewith, stops for limiting the movement of said element between first and second positions, a normally open switch in cooperative relation with said element, a movable armature mounted in cooperative relation with said switch, and means attracting said armature, said switch being closed only by the attraction of said armature when said element is in said first position, the movement or said element to said second position permitting said switch to open.

17. In a device of the character described comprising in combination, a movable member having first and second legs, a first slip friction element on one leg, a second slip friction element on said second leg, a first switch operated by said first element, and a second switch operated by said second element.

18. In a device of the character described comprising in combinatiomamovable armature, first and second spring contact blades normally biased apart carried by said armature, an abutment carried by said second spring contact blade, a movable member, an element adapted to be v moved by said movable member through a slip operating with said abutment to limit movementv of said second contact blade to cause it to engage said first contact blade when said armature Y is attracted, said element releasing said abutment to permit said blades to separate as it moves to said second position.

19. In a device of the character described comprising in combination, an electromagnet including a movable armature, a switch comprising first and second movable contacts, said armature moving said first contact to switch open position and said second contact to the position it occupies when said switch is closed upon deenergization of said electromagnet, said armature moving said first contact to switch closed position upon energization of said electromagnet, resilient means biasing said second. contact-to switch open positon upon energlzation of said electromagnet, a movable member having a first position in which it holds said second contact in switch closed position upon energization of said electromagnet whereby said switch is closed, and means for moving said movable member for releasing said second contact for movement to switch open position under the influence of its bias.

20. In a device of the character described coma prising in combination, a longitudinally movable rod, 9. condition responsive device for moving said rod, a clutch element slidably mounted on said rod and normally in clutched relation therewith, a pair of stops limiting the movement of said element between first and second positions and simultaneously declutching said element with respect to said rod, a relay including a movable armature, a switch controlled thereby, said switch including a movable contact and a continuously biased open contact which normally prevents closure of said switch by the relay, and means controlled by said clutch while in said first position to prevent the movement of said biased contact out of the path of movement of said movable contact as said relay is energized whereby said switch is closed, said clutch in moving to its second position releasing said contact to permit it to move to open position under the infiuence' or its bias.

' JOHN M. WILSON. 

